What is the name of the planet of the Talosians?

The planet of the Talosians is Talos IV.

Talos IV is the homeworld of the Talosians, the powerful telepathic species introduced in Star Trek’s original pilot, “The Cage.” The planet’s surface was devastated by an ancient nuclear war, leaving much of it barren. The surviving Talosians withdrew underground, where they developed extraordinary abilities to create realistic mental illusions and manipulate the perceptions of others.

In “The Cage,” the Talosians use those powers to imprison Captain Christopher Pike and study him as a possible source for rebuilding their population. Their apparent captivity story is more complicated than a simple invasion: the Talosians seek companionship and reproduction after their civilization’s collapse, while Pike struggles to distinguish reality from illusion.

Talos IV later becomes one of Starfleet’s most restricted destinations. In “The Menagerie,” unauthorized contact with the planet is treated as a grave offense, although the prohibition is eventually lifted under exceptional circumstances. The world is therefore important both as the Talosians’ birthplace and as a major early test of Star Trek’s themes of free will, empathy, and cultural misunderstanding.